Using std::vector instead of Array

[rocallahan]

The Array class has almost exactly the same functionality and implementation as std::vector, except that it requires manual cleanup via clear() instead of automatic destruction, and lacks various C++ conveniences like constructors and support for (element : array) syntax. Would you be open to PRs that replace Array usage with std::vector?

Pros: shorter, more idiomatic, somewhat safer C++ code
Cons: would change the C++ API. Are you committed to preserving compatibility with the current API?

[heitzmann]

I don't really like the whole constructor/destructor machinery, but seeing as I have less and less time to dedicate to the project, this change might make it mora approachable to new contributors.

So, I'm open to "modernizing" the code as long as our benchmarks don't suffer significantly.